A conventional heat dissipation module 2 for a central processing unit 1, as shown in FIG. 1, usually comprises a heat radiator 21 mounted on the central processing unit 1 and a heat dissipation fan 22 arranged above the heat radiator 21. The heat generated by the central processing unit 1 is transferred to the heat radiator 21 and then removed with the heat dissipation fan 22. Thus, the operational temperature of the central processing unit 1 can be maintained at a desired level to ensure normal operation of the central processing unit.
The installation of the heat dissipation module 2, as shown in FIGS. 1 and 2, comprises mounting a base 23 to an underside of a circuit board 3 supporting the central processing unit 1. An insulation piece 24 is interposed between the base 23 and the circuit board 3. The insulation piece 24 has a shape exactly corresponding to the base 23. Arms 231 extend from four corners of the base 23. The arms 231 define through holes 2311 through which mounting elements 25 extend. A C-clip 26 is fit over an end of the mounting element 25. Further, four corners of the heat dissipation module 2, e.g., the heat dissipation fan 22, are provided with locking tubes 221, which correspond to the through holes 2311 of the arms 231. The locking tubes 221 receive threaded fasteners 27 extending therethrough. A resilient element 28 is fit over an outer circumference of each threaded fastener 27. Thus, the heat dissipation module 2 can be securely fixed to the central processing unit 1 by extending the threaded fasteners 27 through the locking tubes 221 and through holes 31 defined in the circuit board 3 to threadedly engage the upper, hollow and threaded heads of mounting elements 25 provided on the arms 231 of the base 23.
A coil spring 28 is fit over an outer circumference of the threaded fastener 27 and a lower end of the threaded fastener 27 has a threaded section 271. A circumferential slot 272 is formed at a location above the threaded section 271. An O-ring (or a C-ring or other suitable device) 29 is fit in the circumferential slot 272. The O-ring 29 has on its inner circumference a tongue 291 that extends toward the center. The tongue 291 is engageable with the circumferential slot 272. Thus, after the threaded fastener 27 is inserted through the coil spring 28, and then fit into the locking tube 221, the threaded fastener 27 can be depressed to cause the slot 272 of the threaded fastener 27 to move outside the locking tube 221. At this time, the O-ring 29 is fit over the threaded fastener 27 to securely engage the circumferential slot 272 of the threaded fastener 27. Thus, the lower end of the threaded fastener 27 with the threaded section 271 is kept to project outside the locking tube 221 by the O-ring 29, and is prevented from separating from the locking tube 221. In addition, the upper end of the threaded fastener 27 is not allowed to move through the locking tube 221, and thus, the threaded fastener 27 is retained in the locking tube 221 but is allowed to move up and down to some extent.
To fasten the heat radiator 21 against the central processing unit 1, the threaded fasteners 27 are tightened so that the threaded section 271 of the threaded fastener 27 are screwed into the matching female threads of the mounting elements 25 of the base 23. With the coil spring 28, the heat radiator 21 can be pressed against the central processing unit 1 with some moderate tightness for effecting the transfer of heat from the central processing unit 1. The heat is then dissipated by the heat dissipation fan 22.
The threaded fastener 27 of the conventional heat dissipation module requires an O-ring 29 to keep the threaded fastener 27 from separating from the locking tube 221. Such a design complicates the operation of temporarily retaining the threaded fastener 27 in the locking tube 221. Thus, to simplify the operation of assembling the threaded fastener and the locking tube 221 together is quite a challenge to be overcome by the industry.
Thus, there is a need for an improved fastener, a heat dissipation assembly for a central processing unit, and a method of using the same to overcome the drawbacks of the conventional device.